1. Field of the Invention
The present invention relates to heat sinks for dissipating heat from an electronic device, for example, the CPU of a computer or the like and more particularly, to a heat sink assembly, which is made by fastening a number of radiation fins into a stack.
2. Description of the Related Art
Following fast development of modern information technology, advanced personal computers, PDAs (Personal Digital Assistants), notebook computers of relatively higher operation speed and better computing function have been continuously created. The chips in these advances electronic devices produce much heat during operation. In order to keep normal functioning, heat must Heat sinks and fans are commonly used for this purpose. A heat sink for this purpose generally has a number of radiation fins arranged in parallel on a metal bottom plate. Increasing the installation density of the radiation fins on the metal bottom plate greatly increases the heat dissipation efficiency of the heat sink, however, it will complicate the installation procedure.
FIGS. 8 and 9 show a heat sink assembly according to the prior art. According to this design, the heat sink assembly A is comprised of one front radiation fin A1, one rear radiation fin A2, and a number of intermediate radiation fins A3. The front radiation fin A1 has a bottom mounting flange A11, which defines a coupling groove A111 at the back side. The rear radiation fin A2 has a bottom mounting flange A21, which has a front protruding portion A211 at the front side. Each intermediate radiation fin A3 has a bottom mounting flange A31, which has a rear coupling groove A312 at the back side and a front protruding portion A311 at the front side. By means of engaging the respective front protruding portions A211 and A311 into the respective rear coupling grooves A312 and A111, the radiation fins A1, A2 and A3 are fastened together, forming a heat sink assembly. This design of heat sink assembly still has drawbacks as follows.
1. Because three stamping dies must be prepared for the front, rear and intermediate radiation fins, the manufacturing cost of this heat sink assembly is high.
2. The engagement between the respective front protruding portions and the respective rear coupling grooves cannot prohibit displacement of the radiation fins relative to one another during installation.
3. The design of the front protruding portion and/or rear coupling groove at the bottom mounting flange of each radiation fin consumes much material and requires much labor, thereby increasing the manufacturing cost of the heat sink assembly.
4. The precision of the engagement between each front protruding portion and the respective rear coupling groove is critical, complicating the fabrication of the radiation fins.
FIGS. 10 and 11 show another design of heat sink assembly according to the prior art. According to this design, the heat sink assembly C is comprised of a plurality of radiation fins B arranged in parallel. The radiation fins B each have a flat base B1 and a plurality of mounting flanges B2 respectively perpendicularly extending from the flat base B1. Each mounting flange B2 has a hook B21 at one side and a lug B3 at an opposite side. The lug B3 defines therein a hook hole B31. By means for forcing the hooks B21 of one radiation fin B into hook holes B31 of the lugs B3 of another radiation fin B, the radiation fins B are fastened together, thereby forming the desired heat sink assembly C. This design of heat sink assembly still has drawbacks as follows.
1. The mounting flanges B2 must be bent from the flat base B1 precisely. A small precision error may result in a connection failure between two radiation fins B.
2. The hooks B21 and hook holes B31 of the lugs B3 of one radiation fin B must correspond to the hook holes B31 and hooks B21 of another radiation fin B precisely. A small precision error may result in instability of the connection between two radiation fins B.
3. Every radiation fin B has three mounting flanges B2 with three hooks B21 and three lugs B3. A position error of one hook B21 or lug B3 will result in instability of the heat sink assembly C.
Therefore, it is desirable to provide a heat sink assembly that eliminates the aforesaid drawbacks.